1. Field of the Invention
The present invention relates to a swivel device having a swivel unit disposed in the upper part thereof and being designed to supply electric signals, electric power, and a pressurized fluid to the swivel unit through cables and conduits and more particularly to a swivel device for swiveling the robot motion unit, including a robot arm, of an industrial robot.
2. Description of the Prior Art
An industrial robot, in general, has a construction in which a swivel device is disposed in the base part thereof and a robot motion unit including a robot arm, a robot wrist, and a robot hand is mounted on the swivel device. In such a swivel device, a motor and reduction gear means such as a Harmonic Drive (registered trademark) of a high reduction ratio are built into the swivel device in the central part thereof, and the robot motion unit is turned by the motor through the Harmonic Drive and, in addition, cables are used for supplying electric power to the respective driving motors of the shafts provided in the robot motion unit or are used as signal lines, while conduits are used for supplying pressurized air to the robot hand-operating mechanism. Within the swivel device, the cables and conduits are disposed so as to turn along the outside of a post member enclosing the motor and the Harmonic Drive as the robot motion unit is swiveled. In such a cable and conduit arrangement system, however, since the cables and conduits wind round the outside of the post member enclosing the motor within the swivel device as the robot motion unit is swiveled, the cables and the conduits are caused to move a great degree depending on the outside diameter of the post member. Furthermore, since the post member disposed within the swivel device remains stationary when the robot motion unit mounted on the swivel device is swiveled, the cables and the conduits rub on the surface of the post member as they move, which is liable to cause abrasion in the cables and deteriorates the reliability of the industrial robot. Still further, the above-mentioned construction, in which the motor is disposed in the central part of the swivel device, has a shortcoming in that maintenance works, such as the periodic inspection of the motor or the replacement of the motor, if necessary, are extremely difficult.